In the field of lifting heavy loads, often times the load that is being lifted has a different shape. Such objects may not be readily lifted from a point that is close to the center-of-gravity (“CG”) of the object. Indeed, the lifting point or points may not align with the load CG, which may tend to impart uneven loads to the object or the lifting crane.
To address this issue, when such loads are being lifted, the lifting ropes or slings need to be adjusted, or to adjust for the off CG lifting condition. Historically pulleys or roller rigging blocks have been used that allow for such load adjustment. Various pulleys and equalizer rope blocks have been known and used in the industry for many years. However, such prior art roller rigging blocks primarily have been and are used with wire or metal rope lifting apparatus.
Synthetic rope, and synthetic roundslings are becoming more prevalent in the lifting industry, especially for lifting of very heavy loads. Prior art rigging blocks, designed for use with wire rope, are not well suited to handle synthetic roungslings, which have different physical characteristics than wire rope. For example, many synthetic roundslings have a flatter or wider cross-section than a standard wire rope or cable.
Prior art rigging blocks, used with wire rope and wire cable, are not able to readily maintain such roundsling cross-sections in place in the rigging block, and could cause the wider cross-section roundsling to double over onto itself. There does not appear to be a rigging block, or equalizer rope block that is especially designed to handle the characteristics of a synthetic rope or synthetic roundsling when used in off center lifting operations. The current invention, as described below, teaches such an improved apparatus or equalizer rigging block for use with synthetic rope and synthetic roundslings.